And What If Your Heart Breaks?
by Dawnstorm101
Summary: The spider bite dialed Peter's senses to 11. He can hear heartbeats, smell tears as they form, and feel everything so much more acutely. Normally, he's learned to deal with it, but... what does that mean when Tony dies in his arms?


A/N: Long time no post! There's a good, 16-chapter reason why starring Loki and the Guardians that's graduated to the editing stage, but for now, have this bit of Iron Dad and Spider Son angst! It's based on a Tumblr post by rileywrites-parker about Peter's heightened senses and, being me, I took it in the angsty direction.

* * *

 _Chaotic_ was an understatement about the battle in Wakanda. By the time Peter and the others had arrived, the Wakandan army had already been half decimated, bodies strewn across the once-peaceful plains while the lightly wounded tried to drag the severely wounded to safety. The alien Outriders were only slightly worse off. Even Captain America and Hulk were struggling, the formidable Hulkbuster suit lying in scattered pieces, while Scarlet Witch and Vision lay in a quiet copse, embracing each other even in death.

And between nearly dying on the Q ship, the race to rescue Strange, and the battle on Thanos's homeworld, Peter was already exhausted when they landed in the midst of the chaos. The others were hardly any stronger, but Loki had seen Thor, miraculously alive despite all his worst fears, and plunged into the fray without hesitation. The four Guardians raced to back up Rocket and Groot, and Stephen limped up to Wong's side, the two exchanging a quick hug before resuming the endless battle.

"Stay here," Tony had tried to order before he could leave the shelter of the _Milano_. "Please."

"I _can't_ ," Peter said, already overwhelmed by the sounds of flesh and bone and metal colliding, people screaming in agony and rage and determination, orders and names crisscrossing the air. They reverberated through him, setting his nerves on fire, pounding through his veins like the most potent adrenaline.

It's what had always driven him, those battle sounds he recognized from the night he failed Uncle Ben. Now exponentially worse.

Tony smiled, barely even a quirk of the lips, sending the light dancing across his bruised and bloodied face. Peter could hear his breaths rattling his chest, the bones in his broken arm scraping together. "I know, kid. Just… stick near someone. Anyone. I can't…"

 _I can't lose you,_ neither of them could say, the sentiment hanging in the air between them. As if speaking it would curse them.

"I will," Peter promised.

And Tony leaned in then, unbroken arm lifting, reaching for a hug. But Peter flinched back, away from the brokenness he could hear, the brokenness he wasn't sure how Tony was standing through, let alone fight. The brokenness that he knew would shudder through their contact to make Peter's own heart stutter in agony.

Peter whirled around and leapt into the battle, webs firing, abandoning the hug. Tony froze for half a heartbeat, his arm mercifully silencing, before shaking himself and soaring up to meet Rhodey.

And they fought. Peter's own attacks added to the din, webs slicing through the air, his fists impacting the suit's cushioned interior nanoseconds before the metal sank into an Outrider's flesh. His feet thudded against the ground, air and blood whistling past his ears. The tang of blood stung his nose, Wakanda's natural earthy scents struggling to break through, the stench of death overpowering it all.

Through it all, Peter tracked one person. One voice, laughing, joking with Rhodey and Space Peter through the pain. One heartbeat, pounding irregularly in a beaten chest.

 _Let it beat wrong. Just let it_ beat _._

And, for a time that was both an eternity and the blink of an eye, it did.

An explosion ripped across the plain, tearing through Outriders and Wakandans and superheroes alike. Debris clanged against vibranium, tore through fabric and flesh, bodies ripped apart and slammed into the ground as their owners could do naught but gasp, the concussive force stealing their breath from them.

Peter slammed into the ground, tumbling through the dirt, digging his fingers in to finally bring himself to a halt. He flung his head up, helmet disappearing into his suit as he scanned the new bit of chaos. People raced in, nameless Wakandans, Cap racing towards Black Widow, King T'Challa bounding in with "Nakia!" rolling off his tongue in a scream.

Peter ignored them all, searching for a glint of sunlight off armor, breaking through the ringing in his ears to rediscover that one heartbeat. But he had to rely on his eyes, on seeing Rhodey crash to the ground by a limp body, on hearing his always-steady voice break as he pleaded with Tony to live, to discover that the heartbeat had changed.

There was no rapid, irregular beating anymore.

Instead, all Peter could hear was _thump_ … _thump_ … _thump_ …

He was up and running instantly, heart pounding and blood rushing through his veins, heedless of the danger still raining down around him. Arrows, lightning, green magic, orange magic, they all took out Outriders bearing down on him, but he hardly took notice. He just ran, a single word scraping past his throat, so desperate, so panicked, so loud that his vocal chords ached and it stabbed his eardrums.

" _DAD_!"

Rhodey caught him as he fell, his limbs giving out the second he was next to Tony, the gentle impact shuddering throughout Peter's body, jostling every wound. He whimpered, already detecting the stench of salt as tears welled up. He pressed a hand over a bleeding wound on Tony's chest, the jagged remains of his suit slicing at his tender skin, his hot blood scalding the shaking appendage.

Tony just smiled, broken ribs rattling alongside his arm as he sucked in enough air to whisper, "H-hey, kid."

"Y-you're gonna be f-fine, right, Rhodey?" Peter pleaded, looking up at the soldier. He just lowered his head, his damaged suit creaking as he held Peter tighter.

Tony lifted one heavy hand, his strained grunt reverberating into the fingers pressed against his chest. But still he smiled, ignoring the slowing pulse of his heart to rest his fingers against Peter's cheek. "It's ok," he whispered.

"Yeah, of- of course it is," Peter said, forcing brightness past the lump in his throat. "We can get Loki over here, or- or Stephen, and they can-"

Tony moved his thumb over Peter's lips, hardly any pressure behind the touch, but its deathly chill silenced him. "I love you," he said, his heart thudding against Peter's palm as he added, "son."

Peter sobbed, tears rolling free, pain spiking as they cut through the open wounds on his face. "Don't leave me," he pleaded. "P-please-"

Tony's hand fell away, landing overtop of the one Peter still pressed to his chest, still trying to stem the bleeding, even knowing that wasn't the wound killing him. "Never," he promised. "I'm here. Always."

He gazed at Peter a moment longer, softly, lovingly, as if he were the entire world.

One last breath rattled his bones.

One last heartbeat tapped Peter's palm.

And then… silence. Stillness. His eyes eased shut, his last breath leaving in a gentle puff of air.

Peter's jaws gaped in a piercing wail, tears and spittle mingling as they fell. He leaned over, keeping his hand pressed in place, searching desperately for that heartbeat. His other arm slipped beneath Tony's neck, wrapping tight in the hug he had denied him. And Peter's forehead fell against Tony's, suddenly impossible to hold up. He shook, his sobs making his lungs burn, the stench of blood and death suddenly infinitely worse.

"Peter," Rhodey said gently, arms still wrapped around the grieving boy. "Peter, we can't… you can't stay here."

Peter's gaze darted up, landing on the Titan punching away across the battlefield. His hand clenched into a fist around Tony's shirt, his sobs hardening, deepening into a growl that quaked in his core. "No," he hissed. "I can't."

"Wait, Peter, wait-"

He shoved Rhodey backwards, guilt slicing through him as Tony's best friend hit the ground with a pained groan. But his feet were already carrying him away, another scream shredding his throat. But this one dripped with venom, scalding Peter's tongue, aimed straight at the being who had caused all of the death and agony tearing through Peter.

People yelled at him, chased after him, but all he heard were Thanos's deep, chilling chuckles. Up until the moment he leapt, sailing right over the Gauntleted fist Thanos was too slow to raise, and slammed his fist into Thanos's cheek. The Titan's skin shredded against his teeth as they were shoved from their places, the entire jawbone slamming out of its sockets at the impact of Peter's metal-clad fist. His own fist hit the inside of the suit, obliterating the cushioning, agony ricocheting up his bones as his skin split apart.

Thanos fell, finally properly wounded, something no one else had achieved yet. His body made the ground shake, true fear flashing in his beady eyes. Peter bared his teeth, bringing back his broken arm to rain down revenge, rage exploding within him, begging for an outlet.

But blue and green flashed beside him, sunlight glinting off swords as Nebula and Gamora intervened, driving the weapons straight into Thanos's chest. His dying gurgle jostled Peter, scraping against his eardrums.

And then Thor was there, scooping him up. Peter kicked out, struggling, because _someone_ needed to pay, the rage boiling within needed to go _somewhere_ , _anywhere_ -

The god pinned him against his own body, and Mantis knelt beside them. "Hush, little spider," she murmured, palm against his forehead. Her antennae glowed, more blinding by the second, until the white light encompassed everything, and nothing existed.

Not his pain. Not his happiness. Not his curiosity.

After the grief that swallowed him whole, after the rage that scorched his being, Peter Parker… felt nothing.

And how could Tony be there, always in his heart, if his heart didn't work?


End file.
